Before this upgrading,I drived the platter by a deck motor.I dismantled the simple drive pcb from deck motor，and designed a PLL circuit to replace it.Here are some pics about this DIY:
circuit,PLL IC is SANYO LC7991M:
I etched the pcb by myself and soldered it:
here is the speed photo sensor, black and white strips were atteched on the edge of platter：
The green led will be lighted when the speed is within 33.33rpm+-6%
The final speed is very steady through the control of error DAC in LC7991,test it by 50HZ strobe:
circuit,PLL IC is SANYO LC7991M:
I etched the pcb by myself and soldered it:
here is the speed photo sensor, black and white strips were atteched on the edge of platter：
The green led will be lighted when the speed is within 33.33rpm+-6%
The final speed is very steady through the control of error DAC in LC7991,test it by 50HZ strobe:
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Eaglebear please post your attachments using the forum's server, and post an image of the schematic large enough that members can actually see it.
Hi,nanook!(+-6%) is not the control error,the LC7991 control pins will directly pull high or low when the input signal is out of this range(100HZ+-6%,the crystal is 2.048MHZ,not 11.0592 as schematic),the inner DAC don‘t work.The final control precision is depend on the DAC output,I think the precision should be less than 1%.
Attachment is the datasheet of LC7991.
View attachment 413-12368-0-LC7991M.pdf
Attachment is the datasheet of LC7991.
View attachment 413-12368-0-LC7991M.pdf
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